Converting multiphase current into single-phase current and vice versa



L. SCHGN May 14, 1929.

CONVERTING MULTIPHASE CURRENT INTO SINGLE PHASE CURRENT AND VICE. VERSAFiled May 21, 1925 Fig.2;

Maya; Sag,

Patented May 14, 1929.

UNITED STATES PATENT. OFFICE,

mmwre solicit, or ESSEN, GERMANY, Assnmon 'ro FRIED raceraxrmueasamscam, or ESSEN-ON-THE-RUHB, (mumm VEBSA.

CONVERTING -IUL'.I'.'IPHASE CURRENT INTO SINGLE-PHASE CURRENT LN D VICEapplication filed Kay 21, 1925, Serial-Ho. 31,897, and. in Germany July4, 1924.

The invention relates to devices which serve to convert multiphasecurrent into single phased current and vice-versaand in'which onlystationary windings are made use of for the transmission of energy. Theinvention has for its object to so improve converters of the characterstated that the load is disthe sin le phases of t e multiphase wind ingan simultaneously the phase displacement of the primar,y current 1scompensated and the load maybe considerably increased with this end inview, the invention consists in certain novel features of constructionand combination of parts the essential elements of which are set forthin appended claims, and a preferred form of embodiment of which ishereinafter described with reference to the drawings which accompany andform part of the specification.

. In these drawings:

Fig. 1 isa longitudinal section throughthe converter,-

Fig. 2 is the corresponding wiringldiagram. The converter, Fig. 1,isbuilt in t of an induction motor and has a two-part casing A whichencloses a stator A carrying a three-phase winding-a The stator A hascooperating-with it a body Bwhich is constructed like the rotor of aninduction motor and fitted with a single-phase windin b This body Bwhich is hereinafter denote the stationary rotor, is rigidly mountedonan 'axis 6 fast in the casing A. The three-phase winding a of the-stator A and the singlephase winding 6 of the stationary rotor Bconstitute the power windings of the converter.

.The air-gap existing between stator A and stationary rotor B isenlarged beyond the extent usual in induction motors andsubstanconnected by means of a brass-ring 0 so that all these bars areconnected in parallel and constitute together with the brass-rings emanner bearings 0 This shell-portion is composed 0* a short-circuitwinding which is rotatable about the'common axis of the stator A and bythe rotatingJfield generated in the stator. tributed in a completelumform manner to "There .is arranged on theauxiliary rotor C an excitingwinding 0* which may be connected through slip rings 0 to a source ofconti'nuouscurrent (not shown); The slip rings are arranged on the endfaces of the auxiliary rotor C in the manner, shown in Fig. 1.

Referring to the diagram illustrated in Fig. 2, D denotes a three-phaseinain to which the three-phase stator winding a constituting the primarywinding of the described converter, is connected, 6 denotes, theappropriate single-phase secondary winding of the converter and 0 thesaid exciting winding of the auxiliary rotor C which winding may be(onnected to a source of continuous curren If the stator wound forthree-phase current, of a three-phase motor isconnected to a three-phasemain, while the rotor wound for single-phase current is kept at rest,singlephase' alternating current may be taken, as it is well-known, fromthe rotor winding, this current having the frequency of the threephasemain. A uniform load of all the three phases is, however, impossible inthis case, because the alternating field generated by the single-phaserotorcurrentwill result, together with the constant rotating field ofthe stator, in an elliptical, that is in a non-uniform rotating field.

Now, the line of action of a motor of the character stated the rotor ofwhich is kept at rest, will thor oughl change if an auxiliary rotor C,rotatable about the axis of thestationary rotor and forming ashort-circuit winding, is arranged between the stator A g the stator,when the three-phase primary.

winding a is put in circuit, and will quickly reach a numberoirevolutions dependent on the frequency prevailing in the main and thuson that of the alternating field of the rotor, these frequencies beingequal.

When this phenomenon takes place, a resulting circular rotating fieldwill be formed,

as testings have shown, so that a uniform dis-' As is the case in everyconverter, the primary and secondary winding may be exchanged withoutdifficult-y that is the described device may also serve to convertsingle-phase alternating current into threephased current.

Without deviating'from the spirit of the invention, the construction ofthe auxiliary rotor, C can be altered in several respects. For instance,the iron bars 0 may be replaced by bars made of non-magnetic materialsuch as copper, or, inversely, iron bars may be used instead of thecopper bars. While in the first case the electric properties of theauxiliary rotor C would be improved at the expense of the quality of themagnetic interlinking of stator A and stationary rotor B, in the secondcase the ferro-magnetic shell-portion of rotor 0 would have a doubleobject, viz, to

convey the lines of force of the stator field to the stationary rotor Band to conduct the short-circuit currents. Finally, the shellportioncomposed of insulated iron bars might be replaced by a full drum-shellmade of ferro-magnetic material, whereby the construction of theauxiliary rotor would be simplified.

Claims: 2

1. In a device for converting multiphase current into single-phasecurrent and viceversa a stator carrying one of the converter windings, arotor-like stationary body carrying the other converter winding, asquirrelcage rotor rotatable between said stator and said rotor-likestationary body about the common axis of them, the shell portion of saidrotor at least partly consisting of ferro-magnetic material, an excitingwinding arranged on said rotor and means for connecting the excitingwinding to a source of current.

2. In a device for converting multiphase current into single-phasecurrent and viceversa a stator carrying one of the converter windings, arotor-like stationary body carrying the otherconverter winding, a rotorrotatable between saidstator and said rotor-like stationary body aboutthe common axis of them, metallic end rings on said rotor, iron andcopper bars alternately arranged on said rotor and extending in parallelwith its axis of rotation and connected to said metallic end rings, anexciting winding arranged on said rotor and means for connecting theexciting winding to a'source of current.

3. In 'a device for converting multiphase current into single-phasecurrent and viceversa a stator carrying one of the converter windings, arotor-like stationary body carrying the other converter winding, a rotorrotatable between said stator and said rotor-like stationary bodyaboutthe common axis of thein, a short-circuit winding and an excitingwinding arranged on said rotor and means for connecting the excitingWinding to a source of current.

4. In a device for converting multiphase current into single-phasecurrent and viceversa a stator carrying the multiphase winding, arotor-like stationary body carrying the single-phase winding, a rotorrotatable between said stator and said rotor-like stationary body aboutthe common axis of them, a short-circuit winding and an exciting winding arranged on said rotor and means for conneeting the exciting windingto a source of current.

The foregoing specification signed at C0- logne, Germany, this 24th dayof- April, 1925.

LUDWIG SGHCN.

